In this respect, a method is known from EP 1 995 010 B1 for generating gear teeth having a required crowning and a required twist. For this purpose, a crowned tool is used, on the one hand, which is manufactured in that, on the dressing of the grinding worm, the spacing between the dressing wheel and the worm is changed during the displacement of the worm in the direction of its axis. In this respect, a specific axial spacing is implemented at the worm center and is increased or decreased toward the two worm ends in accordance with the square of the spacing from the worm center. In addition, the axial spacing between the grinding worm and the workpiece is modified during the diagonal feed generating grinding process to generate a crowned modification. The twist itself is determined in two different transverse section planes using the difference of profile angle differences. The method known from EP 1 995 010 B1, however, has the result that shape deviations are present outside the planes in which the twist is determined.
A method is known from DE 10 2012 015 846 in which a specific modification of the surface geometry of a tool is generated in that the position of the dresser for the tool dressing is varied in dependence on the angle of rotation of the tool and/or on the tool width position, wherein the modification of the tool produces a corresponding modification on the surface of the workpiece. In this respect, in particular periodic flank waviness is provided on the active surface of the workpiece as the modification.
It is the object of the present disclosure to further develop the methods for manufacturing a workpiece having a corrected gear tooth geometry in accordance with the prior art and/or to extend their area of application.
This object is achieved by the independent claims of the present disclosure. Advantageous embodiments form the subjects of the dependent claims.
The present disclosure comprises a method for the production of a workpiece having a corrected gear tooth geometry and/or a modified surface structure by a diagonal generating method by means of a modified tool. In this respect, a specific modification of the surface geometry of the tool can be produced in that the position of the dresser to the tool during the dressing is varied in dependent on the angle of rotation of the tool and/or on the tool width position. Alternatively or additionally, as shown at step 1702 of method 1700 in FIG. 17, a specific modification of the surface geometry of the tool can be produced which has a constant value in the generating pattern at least locally in a first direction of the tool and which is given by a function FFt1 in a second direction of the tool which extends perpendicular to the first direction. This modification of the tool produces a corresponding modification on the surface of the workpiece, such as shown at step 1704 of method 1700, by the diagonal generating method. Provision is made in accordance with the present disclosure that the specific modification on the surface of the workpiece is a directed crowning without shape deviations, such as shown at 1706 of method 1700.
The inventor of the present disclosure has recognized that a crowning can be produced on the workpiece by a specific modification of the surface geometry of the tool, which crowning not only has a predefined twist in two planes, but also does not have any shape deviations in all transverse section planes and therefore in a direction perpendicular to the predefined twist or to the extent of the crowning. Such a modification is called a directed crowning here.
The directed crowning which can be produced in accordance with the present disclosure can be free of twist or can have a twist with a freely predefined direction on the tooth flank. A twist-free crowning represents a pure tooth trace modification without any profile modification. This can now also be produced by the method in accordance with the present disclosure on helical gear teeth without shape deviations, i.e. without a profile modification.
The direction of the crowning, i.e. the extent of the modification on the tooth flank can, however, be freely predefined by the method in accordance with the present disclosure. No shape deviations result perpendicular to this predefined direction in accordance with the present disclosure and unlike in the prior art.
The direction of the twist, i.e. the direction of the extent of the crowning on the tooth flank, is may be selected such that the lines of constant modification extend at an angle of less than 60° to the line of action of the gear teeth. The lines of constant modification optionally extends at an angle of less than 30°, further optionally at less than 10° to this line of action. The lines of constant modification may extend in parallel with the line of action of the gear teeth. The crowning of the gear hereby rolls off on a mating-gear.
In accordance with the present disclosure, instead of a natural twist such as arises, for example, with a generation of a crowning by modification of the machine kinematics during the machining process of the workpiece, a crowning can thus be used which extends in a predefinable direction. This has the advantage that a direction of the twist advantageous for the application can be selected instead of the natural twist which typically has a direction unfavorable for the application case.
A directed crowning in accordance with the present disclosure means that the modification on the tooth flank has a constant value in a first direction which is perpendicular to the direction of the crowning or of the twist and is given by a function FFt2 which defines the shape of the crowning in a second direction which defines the direction of the crowning or of the twist respectively. No modifications and thus no shape deviations are thus present perpendicular to the second direction.
Provision can be made in accordance with the present disclosure that a predefined direction of the crowning is achieved by a corresponding choice of the first or second direction of the modification on the tool and of the diagonal ratio, such as also shown at 1706 of method 1700. The first direction of the modification on the tool and the diagonal ratio are in particular selected such that the first direction on the tool is mapped onto a direction extending on the workpiece perpendicular to the desired direction of the crowning.
In accordance with the present disclosure, in a possible embodiment, the directed crowning can be produced only via the modification of the tool and without any modification of the machine kinematics on the machining of the workpiece. Unwanted shape deviations are hereby avoided and the machining process is additionally simplified.
The crowning in accordance with the present disclosure can initially have any desired crowning shape, i.e. can have a maximum point arranged in a middle region from where it falls steadily at the sides. The crowning can in particular be circular or parabolic or logarithmic or can be composed of a plurality of circular, parabolic or logarithmic segments. The crowning is defined by the function FFt2 which is used for producing the modification on the tool and which is transferred to the workpiece with a reverse sign and, optionally, compressed.
The present disclosure comprises a further method for the production of a workpiece having a corrected gear tooth geometry and/or a modified surface structure by a diagonal generating method by means of a modified tool. In this respect, a specific modification of the surface geometry of the tool is produced in that the position of the dresser to the tool during the dressing is varied in dependence on the angle of rotation of the tool and/or on the tool width position. Alternatively or additionally, a specific modification of the surface geometry of the tool can be produced which has a constant value in the generating pattern at least locally in a first direction of the tool and which is given by a function FFt1 in a second direction of the tool which extends perpendicular to the first direction. This modification of the tool produces a corresponding modification on the surface of the workpiece by the diagonal generating method. Provision is made in accordance with the present disclosure that the specific modification is a pure tooth trace modification, such as shown at 1708 of method 1700.
The inventor of the present disclosure has recognized that pure tooth trace modifications can be produced by the method in accordance with the present disclosure, and indeed also with helical gear teeth. In accordance with the prior art, in contrast, unwanted profile modifications, such as an unwanted twist, resulted in addition to the desired tooth trace modifications. The inventor has furthermore recognized that freely predefinable tooth trace modifications can be produced by the method in accordance with the present disclosure.
Provision is therefore made that the tooth trace modification is at least freely defined within specific conditions. The tooth trace modification in particular be predefined as a function FFt2 which is produced on the modified tool and which is then transferred to the workpiece. The position of the dresser to the tool during dressing in particular be varied in dependence on the angle of rotation of the tool and/or on the tool width position in accordance with a function FFt1.
In this respect, the first or second direction of the modification of the tool and the diagonal ratio may be selected such that the first direction is mapped onto a transverse section plane of the workpiece, such as also shown at 1708 of method 1700. This has the consequence that the modification of the tool is imaged with its first direction in which it is constant onto the transverse section plane of the workpiece so that no profile differences are present. The extent of the tooth trace modification is then defined by the extent of the modifications in the second direction.
The present disclosure comprises a further method for the production of a workpiece having a corrected gear tooth geometry and/or a modified surface structure by a diagonal generating method by means of a modified tool. In this respect, a specific modification of the surface geometry of the tool can be produced in that the position of the dresser to the tool during the dressing is varied in dependent on the angle of rotation of the tool and/or on the tool width position. Alternatively or additionally, a specific modification of the surface geometry of the tool can be produced which has a constant value in the generating pattern at least locally in a first direction of the tool and which is given by a function FFt1 in a second direction of the tool which extends perpendicular to the first direction. This modification of the tool produces a corresponding modification on the surface of the workpiece by the diagonal generating method. Provision is made in accordance with the present disclosure that the specific modification is an end relief.
The inventor of the present disclosure has recognized that end reliefs can be produced specifically by the method in accordance with the present disclosure. The end reliefs may be produced with a defined direction. In this respect, a desired direction can in particular be predefined and an end relief can be produced in this direction by a corresponding implementation of the method in accordance with the present disclosure.
In a possible embodiment of the present disclosure, the lines of constant modification can extend at an angle of less than 60° to the line of action of the gear teeth. The lines of constant modification further optionally extend at an angle of less than 30°, further optionally less than 10° to the line of action of the gear teeth. The lines of constant modification may extend in parallel with the line of action of the gear teeth. This has the advantage that the gear rolls off on the end relief.
Alternatively or additionally, the end relief in accordance with the present disclosure can be a generated end relief in which the lines of constant modification have an angle α≠0 with the tooth edge. Such a generated end relief may also be called triangular end relief due to its shape. It allows an improved arrangement of the end relief and an improved running behavior.
The extent of the end relief perpendicular to the lines of constant modification can initially be predefined as desired, wherein the extent optionally falls steadily toward the outside from a region with which the end relief is adjacent to a modified section or a section having a different modification of the gear teeth. The extent of the end relief can in this respect, for example, be planar, parabolic, in the form of a part circle, logarithmic, exponential or elliptical or can consist of such shapes section-wise or can comprise such shapes and transition regions section-wise. If transition regions are provided, they may provide a tangential transition.
The extent of the end relief in particular be planar perpendicular to the lines of constant modification in a first section and can merge in a transition region into an unmodified section or into a section having a different modification. The transition region in particular provide a tangential transition.
As already shown above, in accordance with the present disclosure a direction of the end relief can be predefined and can be implemented by the method in accordance with the present disclosure. In this respect, the first or second direction of the modification of the tool and the diagonal ratio may be selected in dependence on the desired direction of the end relief. The first or second direction of the modification of the tool and the diagonal ratio are in particular selected such that the lines of constant modification on the tool are mapped onto the desired lines of modification of the end relief, such as shown at 1710 of method 1700.
In accordance with the present disclosure, different end reliefs can be provided at the upper edge and at the lower edge of the workpiece. The end reliefs at the upper edge and at the lower edge can in particular differ with regard to their shapes and/or their alignments.
In this respect, end reliefs having different extents of the lines of constant modification can in particular be provided at the upper edge and at the lower edge. Alternatively or additionally, the lines of constant modification can each have different angles α1 or α2 with the respective tooth edge at the upper edge and at the lower edge.
In accordance with a first embodiment of the present disclosure, work can be carried out with different diagonal ratios for machining the two end reliefs. Different directions of the two end reliefs can hereby be brought about.
Alternatively or additionally, the tool can have at least one modified region and one unmodified region. The first end relief can then, for example, be produced via the modified region and the second end relief by a change of the machine kinematics on the machining of the workpiece.
The tool, however, may have at least two regions with different modifications, in particular with modifications having different alignments. In this respect, modifications having different first or second directions can in particular be provided in the two regions. Respective regions having different modifications are hereby used for producing the end relief and the upper edge and lower edge.
Alternatively or additionally, the tool can have two modified regions between which an unmodified region lies. The two modified regions are then used for producing the end reliefs at the upper edge and at the lower edge. The diagonal ratio for the first and second modified regions can be selected differently due to the interposed unmodified region in order thus to set the direction of the end reliefs for the upper edge and the lower edge differently. Work may therefore be carried out with different diagonal ratios in at least two regions.
The two modified regions between which an unmodified region lies can alternatively or additionally also have different first or second directions of the modification.
The present disclosure comprises a further method for the production of a workpiece having a corrected gear tooth geometry and/or a modified surface structure by a diagonal generating method by means of a modified tool. In this respect, a specific modification of the surface geometry of the tool can be produced in that the position of the dresser to the tool during the dressing is varied in dependence on the angle of rotation of the tool and/or on the tool width position. Alternatively or additionally, a specific modification of the surface geometry of the tool can be produced which has a constant value in the generating pattern at least locally in a first direction of the tool and which is given by a function FFt1 in a second direction of the tool which extends perpendicular to the first direction. This modification of the tool produces a corresponding modification on the surface of the workpiece by the diagonal generating method. Provision is made in accordance with the present disclosure that the lines of constant modification on the workpiece extend with an angle of less than 60° to the line of action of the gear teeth.
The method in accordance with the present disclosure may allow the predefinition of the direction of the desired modification which is then provided by the method in accordance with the present disclosure. The direction of the modification may be selected such that a favorable roll-off behavior results.
The lines of constant modification on the workpiece may extend at an angle of less than 30°, further optionally less than 10° to the line of action of the gear teeth. The lines of constant modification may extend in parallel with the line of action of the gear teeth. The workpiece hereby rolls off on the modification and is in contact with the mating gear teeth in each case with a line on which the modification is constant.
In this respect, in accordance with the present disclosure, the first or second directions of the modification of the tool and the diagonal ratio are selected in dependence on the desired direction of the modification or on the desired direction of the lines of constant modification on the workpiece. The first or second direction of the modification on the tool and the diagonal ratio are in particular selected such that the lines of constant modification on the tool are mapped onto the desired lines of modification on the workpiece.
In all of the methods shown above, a modification of the surface geometry of the workpiece may be produced which has a constant value on the tooth flank at least locally in the generating pattern in a first direction of the workpiece and is given by a function FFt2 in a second direction of the workpiece which extends perpendicular to the first direction. The function FFt1 on the tool may be the same function, optionally compressed linearly by a factor, as the function FFt2 on the workpiece. The linear compression relate to the argument of the function and/or to the magnitude of the function. In this respect, the sign of the function naturally changes between the workpiece and the tool since raised points on the tool produce recessed points on the workpiece and vice versa. In particular FFt1 (x)=−FFt2 (cx) apply in the normal section, i.e. a compression is only present with respect to the argument; in the transverse section, in contrast, an additional constant factor k can be present with respect to the magnitude of the function, i.e. FFt1(x)=−k*FFt2 (cx). The factors k and c be larger or smaller than 1 in dependence on the specific conditions.
In all the methods in accordance with the present disclosure, the macrogeometry of the tool and/or the line of action of the dressing tool and/or the diagonal ratio and/or the compression factor can furthermore be selected such that the modification of the tool along a first line on which the contact point moves on the machining of the workpiece on the tool corresponds to the desired modification of the workpiece along a second line on which the contact point moves on the workpiece. The line of action of the dressing tool and the diagonal ratio can in particular be selected such that the first direction of the tool is mapped onto the first direction of the workpiece.
In all methods in accordance with the present disclosure, the specific modification of the surface geometry of the tool can furthermore optionally be produced by a change of the machine kinematics during the dressing process in dependence on the angle of rotation of the tool and/or on the tool width position. This can in particular take place in that one or more of the following corrections of the axial movement with respect to the dressing kinematics are carried out:                a) varying the axial spacing of the dresser from the tool in dependence on the angle of rotation of the tool or on the tool width (infeed);        b) varying the axial feed of the tool or of the dresser in dependence on the angle of rotation of the tool or on the tool width (shift);        c) varying the axial cross angle of the tool and of the dresser in dependence on the angle of rotation of the tool or on the tool width (pivot);        d) varying the speed of the tool in dependence on the angle of rotation of the tool or on the tool width.        
The dressing of the tool can take place with one flank or with two flanks in this respect. A profile roller dresser may be used by means of which the tool is dressed. The dressing of the tooth flank can take place in one or more strokes in this respect.
The profile roller dresser can in particular be in contact with the tooth of the tool during the dressing from the root region to the tip region so that the modification takes place over the total tooth depth in one stroke.
Alternatively, the profile roller dresser can only be in contact with the tooth of the tool in part regions between the root and the tip so that the modification takes place over the tooth depth in a plurality of strokes.
The dressing of the tooth tip can take place via a tip dressing tool.
The present disclosure can in principle also be used with non-dressable tools. In this case, the modifications of the tool are already produced during the manufacture of the tools and cannot be changed during the machining process of a workpiece.
In case of a non-dressable grinding tool, the inventive modification of the surface geometry can be produced during the manufacturing process in exactly the same way as described in the following for dressable tools, with the only change that instead of a dressing tool, a corresponding manufacturing tool is used, for example a rolling die.
In case that the tool is a hobbing cutter, it has to be manufactured in such a way that the enveloping body of the hobbing cutter has the modification provided by the present disclosure. With respect to a hobbing cutter, the term “modification of the surface geometry of the tool” as used in the context of the present disclosure is to be understood as a modification of the surface geometry of the enveloping body of the hobbing cutter.
The present disclosure is however may be used with a dressable tool. In particular, the modification of the surface geometry of the tool may be generated during a dressing step.
The methods in accordance with the present disclosure for the production of a workpiece having a corrected gear tooth geometry and/or a modified surface structure, in which modified grinding worms are optionally used. Dressable grinding worms may be used which are modified in accordance with the present disclosure.
The present disclosure furthermore comprises a gear manufacturing machine for carrying out one or more of the methods presented above. The gear manufacturing machine in particular has an input function and/or calculation function via which a modification and/or the alignment of a modification can be predefined and/or determined. A control function can furthermore be provided which produces the specific modification within the course of the machining of a workpiece.
The input function may allow the input of a desired modification, whereas the calculation function determines the modifications required for its manufacture and/or the changes of the machine kinematics during the machining process and/or during the dressing process required for the production of the modification. In this respect, a control function is optionally provided which correspondingly varies the machine kinematics during the machining process and/or the dressing process.
The machine have one or more of the following functions:
A crowning input function via which one or more parameters of a crowning to be produced can be input. The direction of the crowning can in particular be predefined in this respect. The shape of the crowning can optionally be predefined by the crowning input function. One or more of the following options are optionally available for the shape of the crowning in this respect: circular, parabolic, logarithmic. Alternatively or additionally, the crowning input function can allow the composition of the crowning from a plurality of circular, parabolic and/or logarithmic segments. The size of the crowning can further optionally be predefined.
A tooth trace modification input function. A pure tooth trace modification may be predefined via this input function. The shape of the tooth trace modification may be freely predefined in this respect.
An end relief input function. The end relief input function may allow the predefinition of at least one end relief in this respect. Parameters of the end relief may be input in this respect. The direction, the length and/or the height of the end relief may be predefined in this respect. The shape of the end relief can further optionally be predefined, wherein one or more of the following shapes may be provided for the end relief: planar, parabolic, in the form of a part circle, logarithmic, exponential or elliptical. Provision can furthermore be made that the end relief input function allows the section-wise predefinition of the end reliefs from such shapes and further optionally produces tangential transition regions.
The end relief input function preferably allows the predefinition of end reliefs at the upper edge and at the lower edge. The end relief input function may make possible the predefinition of different end reliefs at the upper edge and at the lower edge in this respect. At least the directions and optionally the size and/or length of the end relief may be input and further optionally the shape of the end reliefs at the upper edge and at the lower edge can be input separately.
The respective input functions preferably allow the input of specific parameters characteristic for the respective predefinable modification.
The gear manufacturing machine preferably has a selection function by which a desired input function can be selected from a selection of at least two of the above-named input functions.
The gear manufacturing machine may calculate the modifications required to produce this modification on the dressing and/or the diagonal ratio required on the machining of the workpiece from the values which are input via the respective input function.
The gear manufacturing machine in accordance with the present disclosure is optionally a gear grinding machine. The gear grinding machine may have a tool spindle, a workpiece spindle and/or a spindle for the reception of a dresser, in particular of a dressing wheel, and machine axes for carrying out the relative movements required by the methods in accordance with the present disclosure between the workpiece and the tool and/or between the tool and the dresser in accordance with the present disclosure.
The present disclosure furthermore comprises a computer system and/or a software program for determining the modification of the tool and/or the required machining parameters on the carrying out of one or more of the methods such as were presented above required for the production of a workpiece having a desired modification. The computer system or software program comprise the function for inputting one of the desired modifications as were presented above. It furthermore comprises a calculation function which determines the parameters of the machining process of the workpiece required for the production of the modification and/or the required modification of the tool and/or the modification of the dressing process of the tool required for providing the modification of the tool from the desired modification of the workpiece. The computer system and/or the software program in particular comprise one of the input functions and/or calculation functions which were described in more detail above with respect to the gear manufacturing machine in accordance with the present disclosure.
The computer system and/or the software program in particular have one or more of the above-named specific input functions and/or the above-described selection functions.
The computer system and/or the software program may have an interface to a gear manufacturing machine and/or the software program can be installed on a gear manufacturing machine so that the changes of the machine kinematics during the dressing process and/or the parameters of the machining process can be predefined and/or determined by the computer system and/or software program. In this respect, a gear manufacturing machine such as was presented above is in particular implemented by the software program in accordance with the present disclosure.
The present disclosure furthermore comprises toothed workpieces such as are produced for the first time by the above-shown methods.
The present disclosure in particular comprises a toothed workpiece, in particular a gear wheel, having a tooth flank modified in crowning form. The crowning is a directed crowning without shape deviations in accordance with the present disclosure. The crowning may be twist-free or has an offset whose direction is selected such that the lines of constant modification extend at an angle of less than 60°, optionally less than 30°, further optionally less than 10° and further optionally in parallel with the line of action of the gear teeth. It in particular it may be a helically geared workpiece.
The present disclosure furthermore comprises a helically geared workpiece, in particular a gear wheel, having a modified tooth flank. Provision is made that the modification is a pure tooth trace modification.
The present disclosure furthermore comprises a geared workpiece, in particular a gear wheel, having at least one end relief. Provision is made in accordance with the present disclosure that the lines of constant modification extend at an angle of less than 60°, optionally less than 30°, further optionally less than 10°, further optionally in parallel with the line of action of the gear teeth.
The present disclosure furthermore comprises a geared workpiece, in particular a gear wheel, having at least one end relief. Provision is made in accordance with the present disclosure that the end relief is a generated end relief, wherein the lines of constant modification extend at an angle α≠0 with the tooth edge.
The present disclosure further comprises a geared workpiece, in particular a gear wheel, in which different end reliefs are provided at the upper edge and at the lower edge. The end reliefs in particular be aligned in different directions and/or have a different shape, size and/or length.
The present disclosure further comprises a geared workpiece, in particular a gear wheel, having a modified tooth flank, wherein the modification has a constant value at least locally in the generating pattern in a first direction and is given in a second direction which extends perpendicular to the first direction by a function FFt. Provision is made in accordance with the present disclosure that the lines of constant modification extend at an angle of less than 60°, optionally less than 30°, further optionally less than 10°, further optionally in parallel with the line of action of the gear teeth.
The geared workpieces are preferably configured such that they have the modifications shown in more detail above with respect to the methods. The geared workpieces in accordance with the present disclosure may be produced by a method in accordance with the present disclosure.
The geared workpieces may in each case be gear wheels. They are optionally helically geared gear wheels in this respect.
Involute gear teeth are preferably produced in accordance with the present disclosure. The modifications indicated in accordance with the present disclosure relate to a modification with respect to a surface geometry given by involute gear teeth. In this respect, involute tools are optionally used which are optionally correspondingly modified.
The present disclosure further comprises a transmission having one or more of the above-described modified workpieces, in particular one or more gears modified in accordance with the present disclosure. It can in particular be a motor vehicle transmission in this respect. The line of the action of the workpieces mentioned above in specific aspects is optionally the line with which a gear in accordance with the present disclosure is in contact with another gear of the transmission on rolling off.
The present disclosure will now be explained in more detail with reference to embodiments and Figures.
The Figures only show w-z diagrams of cylindrical gear teeth by way of example. The w-z diagrams of conical gear teeth are generally not rectangular, are typically trapezoidal, since the evaluation region of the generating path varies over the gear tooth width.